It can get very frustrating for any driver to expect certain acceleration from their car only to find that the car seems to be hesitant while speeding up. This hesitation could be potentially dangerous in situations like entering and exiting the highway from an off-ramp, where acceleration may be required to merge with traffic. A car that struggles or hesitates to accelerate may be unpredictable and moments of hesitation may be coupled with equally dangerous times of surging or unexpected acceleration. When a car is hesitating during acceleration, it should be checked by a mechanic.
How the acceleration system works:
A car with a combustion (gas or diesel) engine need an exact mixture of fuel and air to run efficiently. If this mixture gets thrown off in any way, it may lead an engine running too lean (not enough air), or too rich (not enough fuel). An engine that is hesitating to accelerate is most likely having a fuel/air mixture that is too lean. Engine’s that are running inefficiently will start to show signs like hesitation which will only become worse over time. If you observe some symptoms like hesitation, you should have your car inspected immediately.
Common reasons why this happens:
- Mass Airflow Sensor:The mass airflow sensor measures how much air is entering the engine and sends this information to the car’s computer so that the right amount of fuel can be delivered from the fuel injectors. When a mass airflow sensor starts to fail, it will typically produce an error code or “Check Engine light.” This warning may be followed by hesitation while accelerating, or while driving up a hill. A car with a failing mass airflow sensor may also stall soon after starting.
- Fuel Pump:The fuel pump in most modern cars sits inside the fuel tank and pumps fuel up to the engine. If a fuel pump cannot offer the correct pressure, fuel may have difficulty making it to the engine. A car that hesitates while accelerating or while driving up a hill may be because of a weak fuel pump.
- Throttle position sensor:A throttle position sensor signals the vehicle’s computer how far the throttle is open and how hard the accelerator is being depressed. The computer is then able to adjust the fuel/air mixture going to the engine so that is stays at an appropriate level. If the throttle position sensor is not functioning properly, it may be sending incorrect information to the car’s computer. The computer may then not offer the engine with the correct amount of air while accelerating, creating a hesitation sensation.
- Dirty/failing fuel injectors:Fuel injectors spray fuel in a fine mist into the cylinder where it is mixed with air and ignited by a spark plug. Fuel injectors may get dirty over time and not be able to offer as much fuel to the cylinder as is required. Dirty fuel injectors may make the engine to run lean which will in turn, cause hesitation when accelerating.
How it is done:
A mechanic will first plug into your car’s computer using a code reader/scanner to better identify what the exact issue is. In addition to reading trouble codes, he or she should also be able to take readings of oxygen/fuel intake to make sure those numbers are where they should be. Once the mechanic gets this vital information they can begin to fix any potential problem.
If the mechanic thinks that the mass airflow sensor has gone south or is failing, he or she will first examine the sensor for any superficial damage. The mechanic will also make sure that the sensor is wired correctly and that no damage has been done to the wire harness. The mechanic should then take out the mass airflow sensor and change it with a new one if necessary.
If the mechanic feels the problem is the fuel pump, he or she will remove the fuel tank if necessary to check the pump. If the pump has indeed failed, the mechanic will change it. If the fuel tank itself is beginning to show signs of age, it may be convenient to replace the pump and tank at the same time.
If the mechanic feels the throttle position sensor, he or she will test the throttle position sensor and it’s wiring to see if it is working properly. If it is not, the mechanic will take out the throttle positioning sensor and the wiring and replace them. In between removing the old sensor and changing the new one, the mechanic should take the opportunity to clean the throttle body. The mechanic will then make sure the new throttle positioning sensor is functioning properly and transmitting the correct information to the car’s computer.
If the mechanic is convinced the problem is dirty or failing fuel injectors, he or she will inspect the injectors to inspect for any signs of damage or leakage. The mechanic should also take this opportunity to change the fuel filter if it is not a part of the fuel pump. They will then change the injectors and test them to make sure they are working properly.
In all cases, the mechanic will start the car to make sure that all of the new components are operating properly. In the event that a problem has caused a warning light to come on, the mechanic will be able to clear the trouble code associated with the light using a reader/scanner.
How important is vehicle acceleration hesitation repairs?
Sluggish acceleration can get annoying for drivers who think more power form their vehicle, but it can also be dangerous in certain situations. The unpredictable nature of an engine that hesitates can increase the possibility of a potential accident especially when trying to merge in and out of heavy traffic. If you see that your car seems to be under powered, especially when accelerating, you should not drive it if possible until it can be checked by a mechanic.
SEE ALSO:AUTOMATIC TRANSMISSION HESITATION